You seem to be correct from what I have taken from this post and the AJC. I am sure there are some good, honest open-carriers out there. The very few I have met locally seem to want to make an issue of whether or not a property owners (or their representative) rights, trump their 2A rights. With one exception, that is all I have ever seen.
Perhaps this man has a case, perhaps not. The fact that was he wasnt charged with a weapons offense, and instead charged with trespass says a lot to me.